Aim of this study was to investigate whether octreotide, a synthetic somatostatin analogue that inhibits growth hormone, insulin and glucagon secretion and improves glycaemic control in insulin dependent diabetic patients was able to exert similar effects in insulin treated type 2 diabetic patients with chronic renal failure who have high plasma glucagon levels. For this purpose saline or octreotide was randomly administered by continuous subcutaneous infusion (100 mcg/daily) in addition to usual insulin treatment for 5 days to six type 2 insulin treated diabetic patients with chronic renal failure and to six type 2 patients with normal renal function, as a control group. At day 3 of insulin plus saline or insulin plus octreotide treatment, total glucose uptake and hepatic glucose production (HGP) were investigated during an euglycemic clamp; at day 5 GH, glucagon and C-peptide plasma levels were evaluated. Octreotide treatment lowered endogenous insulin secretion (evaluated by C-Peptide levels assay), GH and glucagon in all patients, but caused a significant reduction of daily insulin requirement (32 +/- 14 I.U. vs 41 +/- 19 I.U., P<0.02) only in patients with renal failure. HGP was significantly (P<0.05) lowered in patients with renal failure but glucose uptake remained unchanged. The lowering effect of octreotide on insulin requirement in diabetic patients with renal failure in spite of the contemporaneous inhibition on insulin secretion could be explained on the basis of the greater reduction of glucagon levels which are very elevated in these patients as compared to patients with normal renal function. The lowering of glucagon could decrease HGP and, consequently, insulin requirement.